Download Chapter 2 Cells

Chapter 2 Cells
Section 1
cell structure
• Common cell traits –
– smallest unit of life
– all cells have an outer covering cell membrane
– every cell has cytoplasm and a nucleus
Comparing cells
• Come in many sizes
• Nerve cells are long and send and receive messages throughout the body
• Cells in plants carry food and water thru the plant
Cell types
• Group 1 – no membrane bound structures or organelles (bacteria) – called
prokaryotic cells
• Group 2 –has membrane bound structures – called eukaryotic cells
Cell organization
• Each cell has a specific function
• Cells take in nutrients
• Cells secrete and store chemicals
• Cells break down substances 24 hours a day
• Cell wall – found only in plant cells
• Tough, rigid outer covering that protects the cell and gives it its shape
• Made mostly of cellulose
• Responsible for support and protection of the plant
Cell membrane
• protective layer around all cells
• Regulates what enters and leaves cell – waste, food, water
Cytoplasm
• Gelatin like substance that fills the cell
• Contains a cytoskeleton to give cell its shape, change its shape or move
Organelles
• Found in eukaryotic cells only
• Each has a specific job within cell
• Similar to organs in animals
Nucleus
• Controls all cell activities – brain of cell
• Separated from rest of cell with its own membrane
• Nucleus contains DNA that is the instructions for each cell
• DNA is the code for the cell’s structure and activities
Energy processing organelles
• Chloroplasts –
– only in plant cells
– Organelle where food is made for plant
– Contain green pigment chlorophyll that captures light energy for
photosynthesis
• Mitochondria
– Help release energy by breaking down food into CO2 and water
– Some more active cells have more mitochondria than other cells (muscles)
• Ribosome –
– helps make the cell’s proteins
– Some float freely, others are attached to the ER
– Receive directions from DNA in nucleus
Processing, transporting and storing organelles
• Endoplasmic reticulum (ER)
– Series of folded membranes in which materials can be processed and
moved around inside the cell
– Can be rough or smooth
• Golgi bodies
– Stacked and flattened
– Sort proteins and other cellular substances and package them into
membrane bound structures called vesicles
– Vesicles deliver substances to areas inside cell and to cell membrane to
release materials out of the cell
Recycling organelles
• Lissome –
– Contain digestive chemicals that help break down food molecules, cell
waste, and worn out cell parts
– Surrounded by membrane that prevents chemicals leaking into the cell and
destroying it
From cell to organism
• Many 1 celled organisms perform all their life functions by themselves
• Cells in many celled organisms do not work alone
– Each cell does its own job, while depending in some way on other cells
• Cells grouped together to do a job are called tissues
• Example – cardiac cells together form cardiac tissue
• Organs are made of a group of two or more tissues working together
• An organ system is a group of organs working together to perform a function
• Ex. Nervous system, excretory system, respiratory system,etc.
Section 2
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viewing cells
Cells are microscopic in size
We use microscopes to magnify the cell using different lenses
Early microscopes
 In the 1600’s, Leeuwenhoek developed the 1st simple microscope using 1 lens
Modern microscopes
• If a microscope has more than one lens, we say it is a compound mic.
• Compound mic, has an eyepiece lens and an objective lens – usually has between
2-4 objective lenses.
Magnification
• The total magnification is found by multiplying the power of the eyepiece times
the power of the objective lens being used
– Ex. Eyepiece = 5x and objective lens =10x
• Therefore, 5x10=total mag. of 50x
Electron microscope
• Used to see things that are too small for other mic. to see
• Can magnify up to 1,000,000 x
• Scanning electron mic. – produces realistic 3d image
Cell theory
• Cells were discovered in 1665 by Robert Hooke
• All organisms are made of one or more cells
• The cell is the basic unit of organization in organisms
• All cells come from other cells
Section 3
viruses
WHAT IS A VIRUS
• A STRAND OF DNA SURROUNDED BY A PROTEIN COAT
• DON’T HAVE NUCLEUS, CELL MEMBRANE OR ORGANELLES
• HAVE A VARIETY OF SHAPES
HOW DO VIRUSES MULTIPLY
• USE A HOST CELL TO MAKE COPIES OF THEMSELVES
• SOME VIRUSES CAN BE STORED FOR YEARS AND SUDDENLY COME
ALIVE AND MULTIPLY QUICKLY
• A VIRUS CAN BE ACTIVE OR LATENT
ACTIVE VIRUSES
 WHEN IT ENTERS THE CELL AND IS ACTIVE IT MAKES NEW
VIRUSES IMMEDIATELY, DESTROYING THE HOST CELL
LATENT VIRUSES
• HEREDITARY MATERIAL OF HOST CELL AND VIRUS COMBINE
• DOES NOT MAKE NEW VIRUSES RIGHT AWAY
• CAN STAY LATENT FOR YEARS, AND UNDER CERTAIN CONDITIONS
CAN ACTIVATE THE VIRUS
HOW DO VIRUSES AFFECT ORGANISMS
• VIRUSES ATTACK PLANTS, FUNGI, PROTISTS, ETC.
• A VIRUS CAN NOT MOVE BY ITSELF
• IT CAN BE CARRIED BY WIND OR INHALED
• MOST VIRUSES AFFECT ONLY ONE KIND OF CELL
• VIRUSES CAN INFECT BACTERIA – CALLED BACTERIOPHAGES
• THEY ATTACH TO BACTERIUM, INJECT DNA AND WITHIN 20
MINUTES EACH INFECTED CELL RELEASES AN AVERAGE OF 100
VIRUSES
FIGHTING VIRUSES
 VACCINES FROM WEAKENED VIRUS PARTICLES
TREATING VIRAL DISEASES
• ANTIBIOTICS ARE EFFECTIVE AGAINST BACTERIAL INFECTIONS,
BUT NOT VIRUSES
• BODY MAKES INTERFERONS TO HELP UNINFECTED CELLS CREATE
DEFENSES
• ANTIVIRAL DRUGS
PREVENTING VIRAL DISEASES
• VACCINATIONS
• IMPROVE SANITATION METHODS
• QUARATINING INFECTED PATIENTS
RESEARCH WITH VIRUSES
 USED IN GENE THERAPY TO SUBSTITUTE NORMAL DNA FOR
THE CELL’S DEFECTIVE DNA, TO CHANGE VIRAL CELLS –
USED TO FIGHT CANCER